Various objects such as semiconductor wafers, masks, printed circuit boards, solar panels and microelectromechanical devices are manufactured by manufacturing processes that are highly complex and costly, comprise multiple stages, and require very accurate machines.
Current demands for high density and performance associated with ultra large scale integration require formation of device features with high precision and uniformity. The usage of such device features necessitates automated process monitoring, including frequent and detailed examination of specimens during the manufacturing process.
The term “examination”, unless specifically stated otherwise, used in this specification in relation to a wafer, should be expansively construed to cover any kind of examination, including but not limited to detection and/or classification of defects in an object (for example, semiconductor wafers) provided by using non-destructive inspection tools. By way of non-limiting example, examination can include generating one or more recipes for examination and/or parts thereof, runtime inspection (e.g. scanning in a single or in multiple scans), reviewing, and measuring and/or other operations provided with regard to the wafer or parts thereof using the same or different inspection tools. Such examination can be carried out by optical examination techniques, charged-particle examination techniques (such as electron beam and ion beam techniques), metrology tools, or any other known technique or tool.
In the context of examination by way of defect detection, in order to find defects, various examination steps can be integrated into the manufacturing process, including inspection and review. The examination steps can be performed a multiplicity of times, for example at certain stages such as after the manufacturing or processing of certain layers, or the like.
The term “defect” used in this specification should be expansively construed to cover any kind of abnormality in examination results or undesirable feature formed on or within a wafer. The term “defect” may relate to a location on a wafer that is identified as a location of a suspected defect, a location of interest representing a location to be further reviewed, and a location that is identified as a location of a redetected defect or a classified defect. A variety of non-destructive inspection tools includes, by way of non-limiting example, scanning electron microscopes, atomic force microscopes, optical inspection tools, metrology, etc. While in some contexts the defect location may refer to a single point, whether in two or three dimensional space, in other contexts the term may relate to a space containing a possible defect, such as a one, two or three dimensional area.
By way of non-limiting example, examination can employ a two phase “inspection and review” procedure.
The term “inspection” refers to scanning and analyzing a wafer or a part thereof, in order to detect locations in which defects may be found. Suspicious locations reported by inspection may include true defects, false positive reports, and nuisance defects, which are harmless.
The term “review” refers to capturing and analyzing one or more specific locations, for example locations of possible defects reported by the inspection process, locations of interest derived from design data, etc. In some embodiments, the term “review” may also refer to, mutatis mutandis, to performing metrology procedures.
Typically, inspection is performed at higher speed and lower resolution than review. Thus, inspection can be used for covering larger areas and detecting possible defects, wherein some or all of which may later be reviewed and examined.
In some embodiments, inspection and review can be performed by different tools, but in other embodiments they can be performed by the same tool.
The complex manufacturing process is not error-free and such errors may cause faults in manufactured objects. Such faults may include defects that can harm operation of the object, false positive findings, which may seem to contain a defect, but no actual defect exists at the area, and nuisances, which may be defects but do not cause any harm or malfunction of the manufactured unit. Errors may include linear or non-linear errors, such as mechanical, electrical or optical errors, in addition to faults in the raw material, human errors and others may cause defects in the wafers. Additional errors may be caused by spatio-temporal factors, such as temperature changes of the wafer, occurring after one or more captures, which may cause slight deformations of the wafer.